Why are we getting more and more depressed?
Lately there is a disease that is gaining ground and does not seem willing to give us respite: depression. The World Health Organization (WHO) estimates that at least 322 million people in the world suffer from it, 18% more than a decade ago.
Also known as major depressive disorder, it is characterized by low mood, decreased interest, impaired cognitive function, and sleep or appetite problems. It is also recurrent and costly, with a tendency to become chronic, and generates suffering and disability.
Do we know what causes it? Unfortunately not. However, there are enough studies on its risk factors, that is, the characteristics and circumstances that increase the probability that we fall into its clutches.
Some, as common sense dictates, are related to dramatic life events, such as the death of a loved one or the diagnosis of a serious illness. However, there are many other risk factors for depression that are not as well known, although they are still important.
We refer to sociodemographic factors, genetic and neurological factors, personal factors, adverse experiences and comorbidity.
Sociodemographic factors: twice as many depressed women
Perhaps the most consistent and well-known risk factor for depression within sociodemographic factors is gender. Universally, regardless of country or culture, women are twice as likely to experience depression as men after puberty.
However, other risk factors for depression have also been found, such as age, marital status, educational level or race. Specifically, this disorder occurs more frequently in young adults; in single, separated or divorced people; and in those with a lower educational level and of white race.
It has also been found that depression is more common in people with low incomes, unemployed people and residents of urban areas.
Genetic factors: the tendency to depression is inherited
First degree relatives of patients with depression show an approximately three times higher risk of developing this disorder. Studies suggest that between 26% and 42% of the variation in depression is due to genetic influences. There are also indications that this heritability is more evident in depressions of early onset and relapsing course.
Still, no specific gene or set of genes has been found to be reliably associated with depression or involved in parental transmission… It's too heterogeneous.
Neurological factors: the amygdala becomes hyperactive
In parallel, neuronal abnormalities have been documented in adults in certain regions of the brain. Structural abnormalities have been found primarily in the gray matter volumes of the hippocampus, amygdala, anterior cingulate cortex, and dorsolateral prefrontal cortex.
Depressing us also changes neuronal function. Specifically, there is increased brain activation in subcortical emotion-processing regions, such as the amygdala and limbic circuits, combined with attenuated activation in cognitive control regions.
It doesn't just happen in adults. The same abnormalities in neuronal function and structure have been identified in children of parents with depression, even before the onset of the depressive episode. And that makes us suspect that they make us more vulnerable to this disorder.
Personal factors: introversion and excessive self-criticism
There is evidence that the tendency to experience negative emotions (fear, anger, sadness, anxiety), as well as mood swings and negative thoughts, implies a greater risk of developing a depressive condition. This is what is known as neuroticism.
On the other hand, there are more cases of depression among people who score high on introversion. It refers to subjects who tend to prefer solitary activities, more focused on their thoughts, feelings and moods than on the search for external stimuli.
Research also suggests a relationship between depressive disorder and a low conscientiousness score, characteristic of aimless, informal, lazy, careless, undisciplined, and low-willed individuals.
Excessive self-criticism (inclination to feelings of guilt and failure derived from unrealistically high expectations of oneself) and dependence/sociotropy (feelings of helplessness and fears of abandonment as a result of a high emotional dependence on others).
Another attitude that promotes depression is what is known as negative attributional style. It is the tendency to explain the negative results of their experiences by internal, stable and global causes. For example, "I didn't get the job because I'm useless, I always have been, in all facets of my life," and similar thoughts.
Something similar occurs with rumination, defined as repetitive thinking that focuses attention on depressive symptoms and their implications, causes, and meanings for the person experiencing them.
Finally, the deficit of personal resources (social skills, appropriate problem-solving strategies or coping skills in stressful circumstances) is also related to a higher risk of depressive symptoms.
More than 40 years of research has documented the role of serious life events in the onset of depression. Depending on the type of sample under study, approximately 50% to 80% of people with depression reported an acute and severe life event before the onset of the disorder.
Based on a conservative estimate, we could establish that people with depression are 2.5 times more likely to have experienced a serious life event before its onset compared to those without. Typically life-threatening health problems, separation and bereavement, exposure to violence, job loss, and financial insecurity.
Equally important is to consider cataclysmic events or phenomena. That is, sudden, single, powerful events that affect large numbers of people, are often beyond the control of individuals or groups, and are assumed to be universally stressful. Like the covid-19 pandemic.
Exposure to negative events in childhood also puts us at risk for depression as we grow up. These events include physical and sexual abuse, psychological neglect (or abandonment), exposure to domestic violence, parental mental illness, and criminality.
People with a history of childhood trauma (especially being bullied and abused or emotionally neglected during childhood) have more than twice the risk of developing depression.
Probably one of the most surprising aspects of depression is that it is often accompanied by other mental disorders. In particular, anxiety disorders, substance-related disorders, eating disorders, and sleep problems.
On the other hand, chronic or serious medical illness is a risk factor for depression. Moreover, an interrelation between depression and a large number of physical diseases has been found: acute myocardial infarction, asthma, cancers, cardiac arrhythmia, chronic coronary syndrome, chronic obstructive pulmonary disease, congestive heart failure, some neurological diseases such as Alzheimer's. or epilepsy, thyroid problems, diabetes, obesity, some pathologies of the digestive system, hypertension, osteoarthritis, osteoporosis, kidney failure, rheumatoid arthritis, stroke... Not forgetting fibromyalgia and chronic fatigue.
Taking all of these factors into account can help prevent, but also help you better understand, depression. And perhaps it will allow us to stop his feet in his unstoppable advance.
This article has been published in The Conversation